In an affidavit read by his lawyer, the 26-year-old is reported as saying: “I fail to understand how I could be charged with murder let alone premeditated murder as I did not intend to kill my girlfriend.”

Prosecutors accuse the Olympic and Paralympic athlete of premeditated murder, with prosecutor Gerrie Nel telling the court that Pistorius – a double amputee – had got up from bed and put on his prostheses before shooting Steenkamp dead through the bathroom door.

But Pistorius told the packed courtroom that he believed his girlfriend was an intruder in the house and felt vulnerable when he heard a noise because he did not have on his prosthetic legs. When he realised afterwards that Steenkamp was not in his bed he said: “It filled me with horror and fear.”

Tweeting from the courtroom earlier today, BBC Africa correspondent Andrew Harding said: “Incredibly compelling testimony from #OscarPistorius and friends.” However, he added: “Statement by #OscarPistorius doesn’t deal with reports of arguments at home that night.”

People have been left stunned over the news of the shooting, with the athlete idolised by many for having helped unite disabled and able-bodied sport.

Known as the “Blade Runner” because he races wearing carbon fibre prosthetic blades, Pistorius made history at London 2012 when he became the first double amputee to run in both the Olympics and Paralympics.

The London 2012 Olympic 400m semi-finalist also won gold in the T44 400m at the Paralympics, setting a Paralympic record in the process, as well as silver in the T44 200m and gold in the 4×100 relay.

But the Guardian has reported how the president of the International Paralympic Committee, Sir Philip Craven, has insisted that the momentum generated by London 2012 will not be halted by recent events.

“I’ve been amazed over the last six months how fresh and bright those memories from London still are in people’s minds,” he told the newspaper.

“This is a major tragedy but we have to differentiate it away from Paralympic sport and the Paralympic movement and what will happen in Sochi [2014] and in Rio [2016].”